Security document

ABSTRACT

A security document with a security element, wherein the security element includes at least partly a material that is optically changeable by an electric or magnetic field. In addition, a corresponding method for producing such a security document and a test method for testing such a security document are described.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional of U.S. application Ser. No.10/511,628, filed Oct. 18, 2004, which is a National Phase ofInternational Application Serial No. PCT/EP03/04006, filed Apr. 16,2003, and claims priority of German Patent Application No. 10217632.9,filed Apr. 19, 2002, the contents of which are hereby incorporated byreference.

FIELD OF THE INVENTION

This invention relates to a security document with a security element, amethod for producing such a security document and a test method fortesting such a security document.

DESCRIPTION OF THE BACKGROUND ART

The use of security elements for protecting security documents has beenknown for some time in a great variety of embodiments. The term“security document” refers here to any document that is to be protectedagainst unauthorized attacks in some way. Documents may have to beprotected against different attacks depending on the type of document orinformation carried by the document.

Certain documents must be protected primarily against forgery and/orfalsification. Such documents include for example bank notes, shares,papers of value, ID cards, certificates, checks or virtually any othertype of official document. With some of these documents, for examplebank notes and papers of value, protection against forgery is mostimportant. Forgery refers here to any imitation of the original, nomatter by what means this is attained. In contrast, checks andcertificates, for example, must be protected primarily againstfalsification of content, since such documents are normally not forgedcompletely but primarily subject to the danger of content being alteredin fraudulent fashion by e.g. forgery of signatures and replacement ofnames or amounts.

Typical security elements that are incorporated into the security paperon which the particular document is printed or into the print itself foravoiding forgery are for example watermarks, security threads, mottlingfibers, holograms or other special printing processes that are difficultto imitate. Security documents, such as bank notes, are normallyequipped with a plurality of different security elements that can betested partly with the naked eye and partly in special test devices byviewing the documents in reflected light, transmitted light orultraviolet light.

Despite the great number of existing different security elements, thereis a continuing need for new, easily checked, safe means of proof thatpermit the authenticity of a document or the correctness of its entriesto be tested.

A second essential security point is protection against unauthorizedperusal and/or duplication of information described on the document byunauthorized persons. Corresponding measures are necessary for examplein confidential documents of research and development departments,military documents, minutes of discussions to be kept secret, e.g. atdiplomatic services, etc. In particular, since the wide spread ofcommonly available copying machines already found in most offices andthe advances in the area of photography, there is an interest inprotecting relevant documents against unauthorized photocopying orphotography.

There are various known security elements in this area as well. In thefirst years following development of the photocopier, confidentialdocuments were covered for example with a red, transparent foil orcoating that absorbed the light of the black-and-white copying machines,which was usually green, and thus made a copy impossible. Besides theannoyance due to the difficult readability of documents thus protected,there is the disadvantage that documents are only protected againstgreen light. Photographic images or copying with more modern copyingmachines with white light are nevertheless possible. In other methods,an embossed transparent foil is applied to the document that acts like aset of prisms and diverts the direction of the light. The prisms can beformed so that one cannot look at the document through themperpendicular from above. This makes it very difficult to make a copy.In newer known methods, phototropic substances are used to protectdocuments. These are chemical compounds whose structures change underthe influence of light. They thus assume a different color and cantherefore protect documents against copying in principle. However, it isproblematic that such phototropic substances often react quite slowly sothat the copy is made faster than the changeover of the substances.Another problem is that such substances cannot prevent documents beingnevertheless copied with reduced light or by other methods. A furtherpossibility for preventing unauthorized copying is to install devices inthe copying machines that recognize security threads, magnetic featuresor other protective devices in the paper of the original and then blockthe copying operation. A great disadvantage of such methods, however, isthat they require installations in the machines and these installationscan be easily bypassed by more or less informed technicians.

A considerable need for novel security elements therefore also stillexists in the area of protection against unauthorized reading or copyingof security documents.

SUMMARY OF THE INVENTION

It is the problem of the present invention to provide a cost-effectiveand simple alternative to the abovementioned prior art that allowsprotection against different possibilities of attack depending on thetype of security document.

This problem is solved by a security document according to theinvention.

According to the invention a security document is provided with asecurity element that is produced at least partly of a material that isoptically changeable by an electric or magnetic field.

By using a material whose optical properties are modifiable by anelectric or magnetic field, the security element can be switched quicklyfrom one optical state to another optical state. There are differentconcrete possibilities of design for protecting the document againstdifferent attacks. This will be explained hereinafter with reference toexamples.

Preferably, the optically changeable material includes a plurality ofparticles that are changeable in their position and/or alignment by theelectric or magnetic field. This can be obtained for example byenclosing the particles in microcapsules, the microcapsules beingbrought into a swollen state by a swelling agent so that the particlesare supported movably within the microcapsules.

Such materials have become known for instance under the catchword“rotating balls” or the brand name Gyricon® from XEROX. These particlesconsist of at least two halves that are differently colored andsimultaneously have different electric properties. The particles can bee.g. white and negatively charged on one side, and black and positivelycharged on the other side. However, any other combination of electricpolarity and color is also possible. All elements working on therotating ball principle can fundamentally also be aligned in a magneticfield if the particles have a magnetic polarity. These particles areembedded in a suitable binder, for example transparent silicone gum.Sheets containing the particles can be produced from the binder. Then aliquid swelling the polymer of the sheet, for example oil orhigh-boiling solvent, is added. Subsequent swelling has the consequencethat the particles are now exposed in a cavity, i.e. in their ownmicrocapsule, which is usually filled with the swelling agent.Alternatively, it is also possible to not form the particles directlyinto a sheet but provide individual particles with a sheath of polymeror another substance. The technology for this corresponds to that usedfor producing microcapsules for pressure sensitive paper. When swellingagent is applied to these individual microcapsules the latter also swelland allow the contained particles to move freely. The particles enclosedin the microcapsules can then in turn be applied to a surface with abinder. When the particles freely movable within the microcapsules areexposed to an electric or magnetic field, the particles will align withthe field lines. The particles thus rotate and turn one of their sidesto the viewer, with a suitable field direction of the particles, so thatthe viewer sees for example either only the black side or only the whiteside in the case of a black-and-white colored particle with suitablepolarity, and the surface of the material thus appears white or black tohim. Instead of a small sphere, any other particle forms canfundamentally also be used, e.g. cylindrical particles.

A special effect can be obtained by using particles having twotransparent hemispheres separated by an opaque layer. Such particles canbe brought by suitable alignment of the electric or magnetic field intoan opaque position in which the opaque separation layer in theindividual particles is perpendicular to the viewing direction. Adifferent arrangement of the field can ensure that the particles alignrotated by 90° and thus the opaque separation layers in the particlesare parallel to the viewer's viewing direction. This causes a layer ofmaterial constructed by the particles to be transparent since the viewercan see between the separation layers of the particles as through aslatted curtain whose slats are aligned parallel to the viewer's viewingdirection.

In an alternative embodiment, a plurality of colored particles areembedded in individual microcapsules in the manner of a powder, wherebytwo different kinds of powder particles having different colors anddifferent electric charges are used. An applied electric field thenensures that one kind of particle moves in the field direction and theother kind contrary to the field direction. If several suchmicrocapsules are located side by side in a layer of material, the colorof the layer of material can consequently be altered—regarded from acertain viewing direction—by accordingly applying a field. Anycombination of particle color and electric polarity can be used heredepending on the case of application.

The stated optically changeable materials are bistable, i.e. theparticles remain in their position and/or alignment until a new field isapplied that aligns them differently or changes their position.

Such materials are finding application in the production of so-called“electronic paper.” The material is used here to form thin sheets by theabove-described method. Then a system of thin electroconductive paths isapplied to the sheet so that an electric field can be locally applied atindividual points of the sheet. This permits the individual points ofthe sheet to be addressed. The individual electrophoretic particles willthen align with the field and one of their optical sides turn upward, orthe corresponding kind of particle within a microcapsule will moveupward toward one electrode and the other kind of particle downwardtoward the other electrode so that a point with a desired color arisesthere. This permits visible characters to be evoked on the sheet. Inpractice these materials are already being used for producing electronicprice labels on supermarket shelves.

It has turned out that such rotating-ball particles or colored powdermixtures located in microcapsules are especially suitable for producingnovel and readily recognizable security elements. No complicatedaddressing or other additional extensive measures during production arerequired. It suffices to apply to the document the optically changeablematerial with the particles in operable form. Therefore, a securitydocument can be provided with the novel inventive security elements inconventional operations as are usual in printing technology.

For this purpose the individual particles can be used for example simplyas pigments of a “printing ink,” i.e. an optically changeable materialis produced that can be processed like a printing ink. The material canbe printed on the document all over in order to produce for example acomplete security layer of the material. Alternatively, any information,for example a text, symbol, logo, etc., can also be produced on thedocument by the material. The carrier material used here may be thecustomary paper used for the particular document. The opticallychangeable material can be applied precisely like any other printing inkby screen printing, intaglio printing, line intaglio printing or anyother expedient method.

According to a first preferred example, the security layer and/orinformation could be produced on the security document here by analready activated optically changeable material, i.e. the information orsecurity layer is printed using particles already sheathed inmicrocapsules. The microcapsules already contain the swelling agent inwhich the particles move. After printing and drying of the material, anoperable security feature arises directly.

In an alternative preferred example, the security layer and/orinformation is first produced on the security document by a nonactivatedoptically changeable material and the security document is then treatedwith a swelling agent to activate the optically changeable material.That is, first only a “printing ink” containing the particles in theirmicrocapsules in unswollen form is used. After printing and after dryingof the print, the individual particles are firmly bound in the ink inimmovable fixation and random alignment. Then the swelling liquid, e.g.an oil, silicone oil preparation, high-boiling solvent or other suitableliquid, is applied to the document. This swelling agent penetrates intothe ink and makes it swell. This causes the spaces to form around theparticles in which the particles are now immovable. The security elementis then operable and can be excited by electric or magnetic fields.

In a further preferred variant, not only particles in microcapsules areadded to the printing ink but additionally the swelling agent inmicroencapsulated form. After drying of the material on the document,destruction of the microcapsules can be obtained for example bymechanical pressure. This releases the swelling agent to act on themicrocapsules of the movable particles as described. Microencapsulatedswelling agents such as high-boiling solvents are known from theproduction of pressure sensitive paper.

In the same way, microcapsules with movable particles—optionally withmicrocapsules with swelling agent—can be incorporated not only inprinting ink but also in writing inks or other coloring agents, whichare then applied to the document as described above. Realizations arelikewise possible for producing ink-jet inks, toners for copiers, laserprinters, etc.

As mentioned above, it is not necessary to apply addressing lines to thedocument for protecting a document by the inventive security elements. Atest can be effected by bringing the security document into an externalelectric field. If for example a printed image consisting of theinventive material has been applied to the document, it can be switchedto one of two positions simply by suitably applying the electric field,so that the applied character becomes visible in a certain color. Whenthe field direction is changed, the color of the character also changes.The same result can be obtained by simply inverting the document in thefield.

Corresponding test devices with electric fields are cost-effective andeasy to produce. The use of the security element is thus in particularalso suitable for mass-produced security documents such as bank notes,since the security element on the bank note can be checked by acost-effective device at any place of payment such as a department-storeor supermarket cash register, gas station, etc.

In an additional variant, a printed security element can be influencedby a time-variant electric or magnetic field. This causes for exampleprinted information to alternately appear and disappear or to movewithin the area. Here, too, it is possible to change the form ofappearance of the character solely by moving the document within theelectric field.

In a further preferred example, the security document is equipped withan at least partly electrically conductive layer for applying anelectric field and/or shielding an electric field. Combinations ofdifferent electrically conductive layers are possible here, whereby theelectrically conductive layers can also be structured.

In an especially preferred variant, at least two conductive layers areelectrically connected by a preferably microelectric circuit. Thiscircuit preferably includes a switchover unit formed so as to switch aconductive connection to a nonconductive state or vice-versa only afterreceiving a security code, for example a password.

The use of such electrically conductive layers or combinations ofconnected electrically conductive layers provides a further plurality ofpossibilities of varying the concrete design of the security elements.

Additional variations can be achieved by constructing the material sothat it is brought into a state in which it is optically changeable byan electric field only by irradiation of light. For example, theparticles of optically changeable material can be adapted to be broughtinto the state in which they are changeable in their position and/oralignment by the electric field by irradiation of light, i.e. particlesare used for example that develop an electric polarity only in light. Itis expedient to use particles having a photoelectrically reacting side.Such particles will be aligned in an electric field only when lightsimultaneously falls on the surface.

Alternatively, the particles of optically changeable material can beembedded in a substance that produces an electric field upon irradiationof light. For example, the binder can be mixed with photoelectricpolymers that develop an electric charge upon exposure to light.Likewise, a further layer producing an electric field upon irradiationof light can be applied to the security document.

If the security element is used for preventing forgery or falsificationof the document, it is expedient to use an optically changeable materialthat is soluble by organic media and/or water. Manipulation of thesecurity document with chemicals and/or water then leads to damage ofthe security element so that the manipulation is noticed at a latercheck.

Since the diverse variants of layers and/or information consisting ofoptically changeable material, of electrically conductive layers and ofphotoelectric materials can be used in any combinations, there is avirtually unlimited number of variations for creating a concretesecurity element by the inventive method. The security element cantherefore be optimally adapted in its properties to the particularpurpose of protection.

For producing forgery-proof documents or documents that are difficult toforge, in particular the following variants are expedient.

In one variant, the side of the rotating-ball particles of inventivematerial that is visible in the normal state and the surroundingprinting ink or a background color have a similar or even identicalcolor. The security element is then not easily noticed. The particlesflip to their other state only by application of the electric field, andthe security element is then switched to a different—preferablycontrasting—color so that a distinctly perceptible change in the imageappears. Different effects can be obtained by suitably selecting theparticular colors on the two halves of the particles. If e.g. afluorescent substance and a nonfluorescent material are used for the twohalves of a particle, the printed information or layer can be visibleonly in UV light in a first orientation, but be visible in normal lightin a second alignment. Likewise, only differently fluorescing ornonfluorescing sides yield an interesting effect only recognizable underUV light. The same effects can be produced by corresponding coloredpowder particles in a microcapsule.

Different variations result from using a material that can be switchedfrom a transparent to an opaque state. The use of particles withtransparent hemispheres and an opaque intermediate layer thus permitsthe intermediate layer to be of reflecting design, for example, so thatin one form of alignment a reflecting surface arises and when anelectric field is applied in another direction a printed image locatedunder the layer appears.

Interesting variants can also be produced by printing a littlestructured or unstructured coating of optically changeable material withelectrically conductive, transparent material or with conductive ink,said electrically conductive layer being structured. This permits anexternal electric field that is basically not or little structured to bemodified in its effect by the conductive overprinting. Structures orcharacters can thus be formed in the field that are not found in thecoating with optically changeable material. Further, it is possible toproduce such characters by using structured electrodes in the testers.For example, a certain character could be printed on one plane of asecurity document and this printed image then overprinted with asecurity layer of inventive material that can be switched from an opaqueto a transparent state. When the security document is later placed in atest device that produces a structured electric field precisely at oneplace, the security layer is switched from the opaque to the transparentstate only in this area, so that it can be tested if the electrodestructures are covered with the printed image located under the securitylayer.

In one example, a transparent, structured, conductive overprint isconnected with an all-over conductive layer on the back of the document.An external field is shorted between the layers and no change in animage appears there, whereas a different optical impression is obtainedby the electric field with corresponding positioning of the opticallychangeable material all around. Any other realizations with the aid ofelectrically conductive printed layers are equally possible.

Especially interesting embodiments result from combining the inventivemethod with other known protecting means. For example, holographicelements on bank notes frequently consist of an embossed synthetic resinbacked with metallic layers. Such elements can be additionally enhancedby a print or frame with inventive layers. If security threads are used,they can be transparent or else metalized. Printing on an inventivematerial with sufficiently fine particles permits characters that can beswitched visible or invisible depending on the alignment of the electricfield to be applied to the security threads. Likewise, a security threaditself, for example, can be switched translucent or opaque if it isproduced from the optically changeable material.

For protection against falsification of content of a security document,in particular one variant is expedient in which information to beprotected is applied to an inventive security layer. The inventivesecurity layer can thus be applied e.g. in a part of the surface of acheck, preferably in the amount field, or in the area of the firstsignature in the case of traveler's checks. The color of this area canbe different from the color of the surrounding check. But it ispreferably very similar or identical, so that the inventive coating isnot noticed. The information to be applied in this area, i.e. thesignature or amount, is then written or printed over the security layer.If a forger attempts to remove by erasure a character present in theoriginal, he will thus remove part of the security coating at the sametime. If the background color matches that of the security layer or thesecurity layer is transparent, he will not notice it. When the securitydocument is brought into an electric or magnetic field for testing,however, the erased part will be immediately noticed. For example, theparticles in the security layer could switch from their invisible to ablack form so that the erased part is immediately recognizable as lighttracks in otherwise black surroundings.

When a soluble binder is used for producing the inventive material, thesame applies to removal of the print by chemical methods. Upon testingin an electric field, traces of wiping are then recognizable, wherebyportions of the inventive material have normally also been blurred inthe surrounding area on the document.

For protecting a security document with secret information againstunauthorized reading or copying, especially the following variants areexpedient.

In a first variant, the document to be protected or at least the areascontaining the information to be protected are covered with a securitylayer that can be switched from a transparent to an opaque state by theelectric field. When the security layer is switched to the opaqueorientation by applying a suitable field, the information on thedocument is no longer visible. When the document is to be used, it mustfirst be switched back to its visible state in an electric or magneticfield.

In a second variant, the information is executed on the securitydocument directly in an ink or toner consisting of the opticallychangeable material. The ink or toner contains as pigments the particleschangeable in their position and/or alignment by an electric field. Theabovementioned black-and-white particles can be used here for example.If a document is prepared in this way with such an ink or toner on whitebackground paper, the information is invisible in a state in which allparticles are so aligned that their white side is directed away from thepaper, i.e. upward. When the document is brought into a suitableelectric field, however, the particles switch and the informationpresents itself black on a white background. This embodiment offersspecial advantages if multicolor documents must be prepared. Suchdocuments can be prepared by using writing inks, printing inks or tonerthat have differently colored particles in each case. The switch to thevisible or invisible state can be performed simultaneously for allparticles.

Further, additional protection can be obtained in such documents byusing electroconductive, transparent layers that cover the document ineach case. A microelectric circuit interconnecting the two layers can beincorporated in the carrier material. If an electric field is appliedfrom outside with an intent to make the document visible, the appliedfield does not affect the inventive material located in the field-freespace between the electrically conductive layers, due to the layersconnected by the circuit. Therefore, it is impossible to switch thesecurity document to its readable state. If the circuit issimultaneously damaged and brought into a permanently conductive stateby such an unsuitable attempt, the document cannot be read at all anymore.

The circuit can be so formed that it must be first addressed by a codeor password and only then interrupts the conductive connection of thetwo sides. Then a suitable electric field can be applied to the documentvia the electrically conductive layers for example by contacting saidelectrically conductive layers with a voltage source. The information isthus switched visible again. After use, the security document can beswitched to the invisible state in the same way by polarity reversal ofthe field and the conductive connection restored between the twoelectrically conductive layers of the document.

For protection against unauthorized copying it is also expedient to useadditional materials, for example as binder in the inventive material oras additional layers that build up electric fields when irradiated withlight. The electrically polarized particles will then align with thefield produced by the photoelectric charge. By suitable execution of thepolarity of the particles in the optically changeable material, thecolor design and the photoelectric properties of the additionalmaterial, the material can be caused to switch to an invisible state asdesired when a maximum allowed brightness is exceeded.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be explained in detail hereinafter on the basis ofexamples with reference to the enclosed figures, in which:

FIG. 1 shows a schematic partial cross section through an inventivesecurity document according to a first example before being brought intoan electric field,

FIG. 2 shows a schematic partial cross section through an inventivesecurity document according to the first example but in an electricfield,

FIG. 3 shows a schematic partial cross section through a securitydocument according to a second example in a first state,

FIG. 4 shows the security document according to FIG. 3 in a secondstate,

FIG. 5 shows a schematic partial cross section through a securitydocument according to a third example,

FIG. 6 shows a perspective plan view of a security document according toa fourth example in a structured electric test field.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows the surface of security document 1 on which security layer2 of inventive material M was produced by a printing operation. This maybe for example unstructured security layer 2 completely covering thesurface of security document 1.

Material M contains here in binder 6 a plurality of microcapsules 7 inwhich individual particles 8 are freely movable floating in a swellingagent. “Pigment particles” 8 are electrically polar and have a blackside and a white side. In the initial state, without a defined electricfield previously acting on the particles, particles 8 are alignedrandomly.

FIG. 2 shows the effect that occurs when this security document isbrought into electric field E. It is assumed here that the black half ofparticles 8 is negatively charged and the white half positively charged.Electrophoretic particles 8 floating freely movably in individualmicrocapsules 7 will then align with applied electric field E inaccordance with their polarity. In FIG. 2 the field is so applied thatparticles 8 all point upward with their black half so that material M,i.e. security layer 2, appears altogether black when regarded fromabove.

It is to be heeded that for clarity's sake the figures showmicrocapsules 7 with particles rather isolated in security layer 2. Inreality, particles 8 or microcapsules 7 are packed relatively denselywithin binder 6. Likewise, for the sake of better representability theindividual layers are not shown in the correct ratios of size.

On white background paper, security layer 2 would be clearlyrecognizable as an all-over black color of the paper. When the electricfield is reversed, the white halves of particles 8 turn upward andsecurity layer 2 becomes virtually invisible. If a structured securitylayer or information is printed on with inventive material M instead ofall-over security layer 2, the electric field can cause the structure orinformation to switch back and forth between a visible and an invisiblestate.

FIGS. 3 and 4 show a further variant. The essential difference over theexamples according to FIGS. 1 and 2 is that individual particles 9 havetwo halves of transparent material that are separated by an opaquemiddle layer. When aligned according to FIG. 3, security layer 2 is thusopaque. Print 10 with certain information applied to document 1 undersecurity layer 2 is then invisible.

FIG. 4 shows the position of particles 8 in case of a field rotated 90°.Here the opaque separation layers within particles 8 are perpendicularto the surface of document 1 so that one can see through security layer2 from above and the information in printed layer 10 becomesrecognizable.

The example according to FIG. 5 involves a variation of somewhat morecomplicated construction in which certain information was applied todocument 1 with inventive optically changeable material M. FIG. 5 showsa section through a printed letter in a greatly enlarged representation.

Specifically, background layer 18, for example a black or dark-graybackground, is printed on the basic material of document 1 here.Thereabove is layer 4 that is produced of optically changeable materialM in the area of the letters to represent information 3, and of furthermaterial 5, for example conventional printing ink 5, in edge areas.Material M again has particles 8 embedded in microcapsules 7 in binder 6as shown in FIGS. 1 and 2. Particles 8 consist here of a white half anda dark colored half. The dark color of particles 8 corresponds preciselyto the color of colored material 5 surrounding information 3. Backgroundlayer 18 also has this color.

In the state shown in FIG. 5 a viewer looking at document 1 from abovewill therefore no longer be able to recognize information 3 applied inlayer 4 in surrounding material 5 by material M. By applying a suitablyelectrically oriented field, particles 8 can be rotated so thatinformation 3 appears white on a dark background and in darksurroundings.

To prevent information 3 on security document 1 from being made visibleat will by applying an external electric field, security document 1 iscoated on each side with layer 11, 12 of transparent conductivematerial, for example a conductive polymer or the like. Layers 11, 12are shorted via lines 14, 15 and microelectric circuit 13, which isprovided for example in the paper of document 1. On the back of document1, i.e. on lower electric layer 11, there are contact areas 17 likewiseconnected via line 16 with microcircuit 13. By inputting an electroniccode via contacts 17 to microcircuit 13 the short between electricallyconductive layers 11, 12 can be eliminated. It is then possible to applya voltage to layers 11, 12 and thus produce a suitable electric field,thereby rotating particles 8 within material M and making information 3visible. By polarity reversal of the electric field, i.e. by reversingthe voltage on layers 11, 12, particles 8 are switched back to the stateshown in FIG. 5. By inputting a further code it can be ensured thatmicrocircuit 13 shorts the two electrically conductive layers again.This again prevents the security document from being made readable inunauthorized fashion by applying voltage to conductive layers 11, 12,i.e. document 1 is protected again.

FIG. 6 shows an example in which security document 1 is coated withlarge-surface security layer 2. In the test device an externalstructured field is applied in which structured metallic electrode 20 isused on the upper side and all-over counterelectrode 19 on theunderside. In unstructured layer 2 on the security document, preciselystructure S of structured electrode 20 is then imaged.

The examples described in the figures are fundamentally also possiblefor particles with magnetic polarity that can be aligned in a magneticfield.

1. A security document (1) with a security element (2, 3) comprising atleast partly of a material (M) that is optically changeable by anelectric field (E) or magnetic field, characterized in that the securitydocument is equipped for the purpose of testing thereof to produce anoptical change of the material (M) by bringing the security documentinto an electric or magnetic field, without any addressing lines beingapplied to the document for this purpose.
 2. A security documentaccording to claim 1, characterized in that the optically changeablematerial (M) includes a plurality of particles (8, 9) that arechangeable in at least one of their position or alignment by means of anelectric field (E) or magnetic field.
 3. A security document accordingto claim 1, characterized in that the security element (3) includesinformation (3) applied to the security document (1) and comprising atleast partly of the optically changeable material (M).
 4. A securitydocument according to claim 1, characterized in that the securityelement (2) includes a security layer (2) comprising at least partly ofthe optically changeable material (M).
 5. A security document accordingto claim 4, characterized in that the security layer has a structure. 6.A security document according to claim 3, characterized in that at leastone of the security layer (2) or the optically changeable information(3) has different colors in dependence on an electric field (E) ormagnetic field from a certain viewing side.
 7. A security documentaccording to claim 3, characterized in that at least one of the securitylayer (2) or the optically changeable information (3) is transparent oropaque in dependence on an electric field (E).
 8. A security documentaccording to claim 4, characterized in that information to be protectedis applied to a security layer.
 9. A security document according toclaim 4, characterized in that a security layer (2) covers information(10) applied to the security document (1).
 10. A security documentaccording to claim 1, characterized in that the material is adapted tobe brought by irradiation of light into a state in which it is opticallychangeable by an electric field.
 11. A security document according toclaim 2, characterized in that the particles of optically changeablematerial are embedded in a substance that produces an electric fieldupon irradiation of light.
 12. A security document according to claim 1,characterized by a layer that produces an electric field uponirradiation of light.
 13. A security document according to claim 1,characterized in that the optically changeable material is soluble by atleast one of organic media or water.
 14. A test method characterized inthat a security document (1) according to claim 1, is exposed fortesting purposes to an external electric field (E) or magnetic field.15. A test method according to claim 14, characterized in that theelectric or magnetic field is structured.